
import cv2
import numpy as np

def nothing(x):
  pass

img=np.zeros((300,512,3),np.uint8)
cv2.namedWindow('image')
cv2.createTrackbar('R','image',0,255,nothing)
cv2.createTrackbar('G','image',0,255,nothing)
cv2.createTrackbar('B','image',0,255,nothing)
switch='0:OFF\n1:ON'
cv2.createTrackbar(switch,'image',0,1,nothing)

while(1):
  cv2.imshow('image',img)
  k=cv2.waitKey(1)&0xFF
  if k==27:
    break
  r=cv2.getTrackbarPos('R','image')
  g=cv2.getTrackbarPos('G','image')
  b=cv2.getTrackbarPos('B','image')
  s=cv2.getTrackbarPos(switch,'image')
  if s==0:
    img[:]=0
  else:
    img[:]=[b,g,r]#OpenCV存储颜色顺序是BGR
cv2.destroyAllWindows()
